calculated  from  the  percentage  present  in  the  plasma  after  injection, 
and,  as  the  relation  between  the  volume  of  the  red  cells  and  that  of 
the  plasma  had  previously  been  deternhnefl  by  the  aid  of  the 
haemocrit,  the  total  volume  of  the  blood  was  also  by  this  means 
ascertained*  As  time  went  on  the  amount  of  haemoglobin  in  the 
rabbit’s  plasma  diminished  at  first  rapidly,  then  more  slowly,  until 
at  the  end  of  twenty-four  hours  the  amount  present  was  less  than 
0'2  2aer  cent. 
The  first  specimen  of  the  urine,  after  intravenous  injection  of 
dissoh'ed  haemoglobin,  was,  in  all  experiments  except  the  first  two, 
m  which  the  tint  was  lighter,  porter  coloured  in  a  layer  two  inches  or 
more  in  thickness,  and  dark  red  or  reddish  brown  in  a  layer  one 
centimetre  thick.  The  percentage  of  haemoglobin  ranged  from  5'o 
per  cent,  to  0‘6  per  cent.,  reaching,  however,  in  one  experiment 
O'op  per  cent.  In  succeeding  specimens  of  the  urine  the  amount  of 
haemoglobin  usually  became  progressively  smaller,  and  at  the  end  of 
twenty-four  hours  disappeared.  The  total  amount  of  haemoglobin 
eliminated  in  the  urine  after  injection,  rang'ed  in  the  experiments 
made  between  o  2  g.  and  i'34  §'•  These  a.mounts  refer,  however,  only 
to  unaltered  haemoglobin.  In  addition  a  relatively'  small  amount  of 
haemoglobin  was  broken  up  in  the  urine,  to  which  it  imparted  a 
brownish  tint.  The  actual  amount  of  haemoglobin  passing  into  the 
urine  would,  therefore,  be  slightly  greater  than  the  amounts  given  in 
Column  6,  Table  35.  To  obtain  some  idea  of  the  total  haemoglobin 
discharged  into  the  urine,  a  given  volume  of  the  urine  was  rendered 
slightly  acid  with  acetic  acid,  boiled,  and  the  volume  of  the  resulting 
chocolate  coloured  precipitate  measured  after  centrifugalisation  in  a 
graduated  tube.  By  comparison  with  a  parallel  series  of  experiments 
111  which  known  amounts  of  red  cells  were  laked  and  added  to  urine, 
the  volume  of  the  precipitate  obtained  after  acidifying  and  boiling 
being  carefully  noted,  the  amounts  of  haemoglobin  originally 
discharged  into  the  urine  were  determined.  The  percentages 
obtained  in  this  way  were  larger  than  those  given  by  haemoglobino- 
metei  readings  of  the  diluted  urine,  by  an  amount  not  exceeding 
25  per  cent.  In  these  experiments  the  precipitate  produced  in  the 
in  the 
For  further  details  cp.  A  method  of  estimating  the  total  volume  of  blood  coutained 
living  body,  Proceedings  of  the  Royal  Society  of  London,  1909,  Series  B.,  vol.  8l. 
